There have been many small-scale investigations into whether or not prayer works - most of them by believers, and most of them using poor research methods or poor statistical techniques. Christian publishers and evangelical journals produce volumes of stories of prayers that have been answered1 - always in the affirmative - by God. The most basic next step would be to compare these to how many have not been answered, in order to see if it is mere luck that some events go favourably. Don't forget that "people speak confidently about the power of prayer, but in war both sides pray for victory"2. All the larger studies, and the well-controlled ones, show that prayer has no effect on the world. The largest study, ran mostly sensibly by a Christian think tank, found to their own embarrassment that not only did prayer have no effect on cardiac patients but that by telling one of the groups that they were being prayed for, they made their recovery worse by making them worry more.3,4,5,6,7,8,9. Aside from individual effects, because of the large volume of prayers that occur in the world, their cumulative effects should be statistically observable. But no such evidence can be found. Prayer doesn't help individual patients, and, it has no effect on overall national welfare rates10.

1. Scientific Studies of Prayer

The Nobel-prize winning physicist scientist, Victor Stenger, has researched the possible effects of prayer on the real world and presents some of his results in "God, the Failed Hypothesis: How Science Shows That God Does Not Exist11". He says that "the effects of prayer should be readily measurable [...] but, once again, we find that none of the reports is convincing. [...] Every published claim of a positive effect of which I am aware fails to satisfy one or more [sensible] methodological conditions. [...] With all the publicity that attends to prayer studies, it is highly unlikely any good quality study has been missed"5.

Kenneth W. Krause in the Skeptical Inquirer (2008)3 highlights some more studies: MANTRA (Monitoring and Actualization of Noetic Training) and the MANTRA II studies published by Mitchell Krucoff and others in 2001 and 2005, later published in The Lancet, involved 748 angioplasty or cardiac catheterization patients. The experiments confirmed that prayer had no effect.

And, earlier:

“In 1982 Randolph Byrd, MD, a San Francisco cardiologist, enlisted 393 cardiac patients in the San Francisco General Hospital into a double-blind, randomized study to determine whether intercessory prayer, directed to the Judeo-Christian God, had any effect on their medical condition. [...] Byrd identified six categories in which the prayed-for group did marginally better. The press reported these six categories as proof of the power of prayer, but of course that leaves twenty categories in which patients did not do better and may have done worse.”

1.1. Francis Galton (1872)

The early scientist Sir Francis Galton, Charles Darwin's cousin, was the first to analyse statistically whether or not praying for people works4,8. He published his results in "Statistical Inquiries into the Efficacy of Prayer" in 18728.

“[He] calculated the average longevity of British monarchs and archbishops of the Church of England. Since the Daily Order for Prayer of the Anglican Church calls for prayers for the long life of the monarch and for the archbishop, Galton pointed out that they must surely be the most prayed-for people in all of England. Because these powerful people would have access to the best medical care, you might expect monarchs and archbishops to live longer than ordinary folk, with or without intercessory prayers on their behalf. Galton, however, discovered that on average they lived no longer than their subjects. Perhaps that reflects the pitiful state of medical knowledge in Victorian England. In any case, as Galton showed, intercessory prayer did not prolong the lives of British monarchs and archbishops.”

“Francis Galton... noted that every Sunday, in churches throughout Britain, entire congregations prayed publicly for the health of the royal family. Shouldn't they, therefore, be unusually fit, compared with the rest of us, who are prayed for only by our nearest and dearest? Galton looked into it, and found no statistical difference. His intention may, in any case, have been satirical, as also when he prayed over randomized plots of land to see if the plants would grow any faster (they didn't).”

1.2. The John Templeton Foundation's Great Prayer Experiment (2006)

A large prayer study was orchestrated by The John Templeton Foundation, whose purpose it is to further the spread of Christianity3. It was called the Study of the Therapeutic Effects of Intercessory Prayer (STEP) and amidst high expectations it was known as 'The Great Prayer Experiment'. The study was led by Dr Herbert Benson, of the Mind/Body Medical Institute near Boston, USA4. The study lasted almost a decade9 and involved 1802 patients who were recovering from heart surgery3,4. It is introduced below by Prof. Richard Dawkins:

“Valiantly shouldering aside all mockery, the team of researchers [...] soldiered on, spending $2.4 million of Templeton money. [...] Prayers were delivered by the congregations of three churches, one in Minnesota, one in Massachusetts and one in Missouri.”

The results were published in the American Heart Journal in 2006 Apr4,9, showing how each of the 3 groups of patients were helped (or not) by the prayers:

Group 1: Received prayers, but were not told about them. This tests if prayers helped them recover more than normal patients. Their recovery was average.

Group 2: Received no prayers, and were not told so. This tested if there was something about the experiment that was affecting the results. Their recovery was also average.

Group 3: Received prayers and were told so. This tested the psychosomatic effects of knowing that one is being prayed for. This group "suffered significantly more complications".

The prayers had no positive effect3,4,9. This was embarrassing for the researchers (and Templeton fans) but madly entertaining for many observers.

“This was the largest and most rigorous study of the efficacy of prayer that had ever been attempted [...]. The conclusion of the study was that prayers offered by strangers had no effect on the recovery of people undergoing heart surgery. [...] The only surprise was that a slight increase in complications was found in a subset of patients who were told that strangers were praying for them. The knowledge that they were being prayed for seemed to interfere with healing [and] was attributed by the authors to "performance anxiety." Presumably, being on God´s team put them under greater stress. It raised a question about whether it was a good idea to let people know they were being prayed for. Otherwise, there was no difference.”

One of the STEP researchers, Dr Charles Bethea, says that those who knew they were being prayed for suffered more stress because they worried more about their own condition, and evolutionary biologist Prof. Richard Dawkins agrees4 as does the academic scientist Robert K. Park9. What amazing results! In conclusion, Prof. Dawkins asks a light-hearted theological question:

“Was God doing a bit of smiting, to show his disapproval of the whole barmy enterprise?”

“The Muslim has experienced his own prayer successes that confirmed to him that Allah is the only true god. What about Jews who pray in their particular way to their god? They say their prayers get answered too. Millions of Hindus claim positive results from their prayers.”

If prayer worked, then, it should be apparent that highly religious countries have a statistically detectable betterment of their lives and fortunes in some areas of life. In 50 Reasons People Give for Believing in a God12, Guy Harrison argues that the prayers that are the most heartfelt, passionate, honest and sincere are those of a mother for her own infants. So, if we compare poor countries, infant mortality should be negatively correlated with belief in God. But the data shows this to be untrue.

“... there are many highly religious nations with horrible infant mortality rates. Meanwhile, highly secular nations with large percentages of atheists in their populations have very low infant mortality rates.”

The chart above shows the Infant Mortality Rate, measured in deaths per 1000 live births, against the rate of god-belief. All developed countries sit along the bottom, no matter what their level of belief in God is. For example, Poland has a good infant mortality rate of 4/1000, and only 3% of the population disbelieve in God. Nearby Estonia has a similar infant mortality rate (3/1000) but a full half of the population do not believe in God. This means that richer countries experience better infant mortality rates, and prayer does not make a difference to them. A huge number of poor countries, where rate of belief in God is very high, sit along the left. This means that in poor countries, infant mortality rate is high, and, so is the extent to which mothers are praying for their children. This means that praying, compassionately and desperately, for the health of their own children does not work. But the ultimate comparison is within demographic areas. Very poor countries such as Vietnam have the same infant mortality rate as their near neighbours, but, have a completely different rate of praying (due to a high level of disbelief in God). What this shows us is that internationally, on average, and, compared to their neighbours, rich and poor countries' infant mortality rates are not affected by the rate of belief in God. In other words, prayer is making no difference.